Locking means for a rotational work station in an analyzer

Abstract

There is disclosed a camming apparatus for a work station that provides for relative rotational motion between a cam and a cam follower connected to the work station, e.g., a liquid dispenser. The cam follower is movable on a carrier that frictionally engages the cam, unless the carrier is restricted. The cam is rotated by a gear. A locking mechanism is provided to lock the carrier against inadvertent rotation, and the improvement resides in the locking mechanism comprising a gear segment on the cam follower positioned to engage the gear during a portion of the engagement by the drive gear of the gear segment on the cam.

What is claimed is: 
     
       1. In a camming apparatus for raising and lowering a work station in response to a rotational drive, said apparatus comprising a cam, means for mounting said cam for rotation, drive means for rotating said cam and including a drive gear and a gear segment on said cam, a carrier for mounting a cam follower on said cam, said carrier being frictionally mounted on said cam sufficient to cause said follower to rotate with said cam, unless said carrier is held from rotation, and locking means to lock said carrier into a known position to permit adjustments, the improvement wherein said locking means comprise a gear segment having two ends on said carrier positioned to engage said drive gear during a portion of the engagement by said drive gear of said gear segment on said cam.   
     
     
       2. Apparatus as defined in claim 1 wherein said gear segment on said carrier includes engaging means for smoothly engaging said drive gear as said carrier segment moves into the path of said drive gear. 
     
     
       3. Apparatus as defined in claim 2, wherein said engaging means comprise the sizing of the very first gear tooth in said carrier gear segment at each of said ends so that its height is less than the distance of projection of one pitch circle. 
     
     
       4. Apparatus as defined in claim 3, wherein at least one of the next two of said gear teeth immediately following said very first gear tooth has a height that approximates said distance of projection of said pitch circle. 
     
     
       5. Apparatus as defined in claim 1, wherein said locking means is free of activating means actuated apart from said drive gear. 
     
     
       6. In a gear drive comprising a drive gear and a segment of a driven ring gear that rotates into and out of engagement with said drive gear along a pitch circle, said ring gear segment having opposite ends with gear teeth extending at uniformly spaced intervals between said ends, the improvement wherein said gear segment further includes at said opposite ends means for smoothly engaging said drive gear as said segment moves into the path of said drive gear, said means comprising the sizing of the very first gear tooth in said segment at each of said ends so that its height is less than the distance of projection of said pitch circle.   
     
     
       7. A gear drive as defined in claim 6 wherein at least one of the next two of said gear teeth immediately following said very first gear tooth has a height that approximates said distance of projection of said pitch circle.